This invention relates in general to artificial dental prostheses, more particularly to prostheses retained on a supporting post or posts with a cement (i.e. a cement-retained prostheses) or otherwise. The supporting post may be an endodontic post supported in the patient's natural root or it may be an abutment fixed in an artificial root, commonly called a "dental implant," implanted at an edentulous site in the patient's jawbone. The invention is herein described and illustrated in the latter environment wherein an artificial tooth is fixed on an abutment which in turn is fixed to the dental implant.
Cement-retained prostheses are formed to enclose the supporting post or abutment and to fit tightly at the margin with the implant or natural root. In the illustrated case employing dental implants, the margin is a prefabricated surface of the implant or of a distancing member supported on the implant. This prefabricated surface can be made with engineering precision, and it is desired that the prosthesis (i.e. artificial tooth) be made with equal precision in order to provide a uniformly tight margin that will exclude oral fluids and provide long-term hygienic conditions at the margin. At the same time, the dental abutments that are used with dental implants frequently are fitted with antirotational holding structures, such as a flat surface(s) or a groove(s), to engage a prosthesis against rotation around the abutment, which is particularly useful when a single tooth is being restored. The present invention enhances the opportunity of restorative dentists and dental laboratories to achieve an ideal margin by removing the inaccuracies that may sometimes be encountered during the impression-making process within the patient's mouth at the margin. Further, the inventive coping can be used to provide accurate anti-rotational structures on the artificial tooth that are to engage the corresponding antirotational structures of the supporting abutment post.